This invention relates to a nut disengagement prevention structure, and more particularly to a nut disengagement prevention structure of the type in which a nut, once threaded onto a bolt, is held against withdrawal unless an artificial external force is exerted on the nut.
For example, for connecting a battery cord 3 to an electrode 2 of a battery 1 mounted on an automobile, an annular connection portion 4a of a battery terminal 4, press-fastened to a distal end of the battery cord 3, is fitted on the electrode 2, and then a bolt 5 is passed through passage holes 4c, formed respectively through a pair of clamping piece portions 4b and 4b, and is tightened to be fastened, together with a washer 6, to a nut 7. As a result, the annular connection portion 4a is deformed to be reduced in diameter through the pair of clamping piece portions 4b and 4b, so that the battery terminal 4 is fixedly secured to the electrode 2.
For effecting the above operation in the vehicle-assembling process, the bolt 5, passed through the passage holes 4c, is beforehand loosely tightened relative to the nut 7. Namely, the battery terminal 4, having the bolt 5 and the nut 7 beforehand connected thereto in an integrated manner, is fed to a production line where the nut and the bolt are finally completely fastened together.
In such form of use, however, the nut 7 is often disengaged from the bolt 5 by vibrations, an impact and the like during the transport of the battery terminal 4, and the nut 7 need to be again attached to the bolt, and in some cases the nut is lost.
Therefore, there has been proposed a nut disengagement prevention structure (disclosed, for example, in JP-A-10-61647) for preventing the disengagement of a nut from a bolt, in which an E-ring or a retaining cap is fitted on a distal end of the bolt, or an internal thread portion is formed in the distal end of the bolt, and a small screw, having a head larger in diameter than a thread ridge, is threaded into this internal thread portion, or an enlarged-diameter portion is formed at the distal end of the bolt by an expanding slot or a stamped section.
Another nut disengagement prevention structure is provided by coating, for example, a coating material, an adhesive or the like onto the distal end of the bolt.
In the above nut disengagement prevention structures, however, the pre-processing step for the bolt or the post-processing step, such as the operation for attaching the retaining member to the bolt after the bolt is threaded into the nut, the diameter-enlarging operation, or the coating operation, is added, and therefore there were encountered problems that the mounting operation is troublesome, and required much time and labor, and that the production cost increased because of the increased number of the component parts.
It is therefore an object of the present invention to provide a nut disengagement prevention structure and a battery terminal incorporating the same, in which the disengagement of a nut can be easily prevented with the simple structure.
In order to achieve the above object, according to the present invention, there is provided a nut disengagement prevention structure comprising:
a bolt, having an external thread; and
a nut, thread on the bolt, having an internal thread;
wherein the thread portion which is the closest to a leading end of the bolt has a first minor diameter;
wherein any other portion of the thread of the bolt has a second minor diameter which is smaller than the first minor diameter; and
wherein the second minor diameter is substantially identical with a minor diameter of the internal thread of the nut.
In this construction, when the bolt is tightened relative to the nut with a turning torque of above a predetermined value, the nut is threaded toward a proximal end of the bolt, while an internal thread of the nut and the thread portion which is the closest to a leading end of the bolt, engaged with each other, are resiliently deformed.
The second minor diameter of the any other portion of the thread of the bolt is substantially identical with the minor diameter of the internal thread of the nut, and therefore an ordinary tightening operation can be effected.
Therefore, the nut, once threaded onto the proximal end of the bolt, is held against withdrawal from the bolt unless a turning torque of above a predetermined value is artificially exerted on the nut.
According to the present invention, there is also provided a nut disengagement prevention structure comprising:
a bolt, having an external thread; and
a nut, thread on the bolt, having an internal thread;
wherein the thread portion which is the closest to a leading end of the bolt has a first major diameter;
wherein any other portion of the thread of the bolt has a second major diameter which is smaller than the first major diameter; and
wherein the second major diameter is substantially identical with a major diameter of the internal thread of the nut.
In this construction, when the bolt is tightened relative to the nut with a turning torque of above a predetermined value, the nut is threaded toward a proximal end of the bolt, while an internal thread of the nut and the thread portion which is the closest to a leading end of the bolt, engaged with each other, are resiliently deformed.
The second major diameter of the any other portion of the thread of the bolt is substantially identical with the major diameter of the internal thread of the nut, and therefore an ordinary tightening operation can be effected.
Therefore, the nut, once threaded onto the proximal end of the thread portion of the bolt, is held against withdrawal from the bolt unless a turning torque of above a predetermined value is artificially exerted on the nut.
According to the present invention, there is also provided a nut disengagement prevention structure comprising:
a bolt, having an external thread; and
a nut, thread on the bolt, having an internal thread;
wherein adjacent thread portions which are closest to a leading end of the bolt are provided with a first pitch;
wherein each of any other adjacent thread portions of the bolt are provided with a second pitch which is different from the first pitch; and
wherein the second pitch is substantially identical with a pitch of each adjacent thread portions of the nut.
In this construction, when the bolt is tightened relative to the nut with a turning torque of above a predetermined value, the nut is threaded toward a proximal end of the bolt while an internal thread of the nut and the thread portion which is the closest to the leading end of the bolt, engaged with each other, are resiliently deformed.
The second pitch each of the any other adjacent thread portions of the bolt is substantially identical with the pitch of each adjacent thread portions of the nut, and therefore an ordinary tightening operation can be effected.
Therefore, the nut, once threaded onto the proximal end of the thread portion of the bolt, is held against withdrawal from the bolt unless a turning torque of above a predetermined value is artificially exerted on the nut.
Namely, in the bolt having the above nut disengagement prevention structures, only the thread portion which is the closest to the leading end of the bolt need to be formed into a thread configuration slightly different from the specification dimension during an ordinary bolt-producing process, and any special pre-processing step, such as the formation of an expanding slot or a stamped portion at the distal end of the bolt, and any post-processing step, such as the mounting of a retaining member, as used in the related technique, are not necessary, and the number of the component parts will not increase.
Therefore, there can be provided the inexpensive nut disengagement prevention structure in which the disengagement of the nut can be easily prevented with the simple structure.
According to the present invention, there is also provided a battery terminal comprising:
a connection member, fitted with a battery post of a battery;
a pair of clamping portions, extended respectively from both ends of the connecting portion;
a bolt, having an external thread; and
a nut, thread on the bolt, having an internal thread;
wherein the thread portion which is the closest to a leading end of the bolt has a first minor diameter;
wherein any other portion of the thread of the bolt has a second minor diameter which is smaller than the first minor diameter; and
wherein the second minor diameter is substantially identical with a minor diameter of the internal thread of the nut.
According to the present invention, there is also provided a battery terminal comprising:
a connection member, fitted with a battery post of a battery;
a pair of clamping portions, extended respectively from both ends of the connecting portion;
a bolt, having an external thread; and
a nut, thread on the bolt, having an internal thread;
wherein the thread portion which is the closest to a leading end of the bolt has a first major diameter;
wherein any other portion of the thread of the bolt has a second major diameter which is smaller than the first major diameter; and
wherein the second major diameter is substantially identical with a major diameter of the internal thread of the nut.
According to the present invention, there is also provided a battery terminal comprising:
a connection member, fitted with a battery post of a battery;
a pair of clamping portions, extended respectively from both ends of the connecting portion;
a bolt, having an external thread; and
a nut, thread on the bolt, having an internal thread;
wherein adjacent thread portions which are closest to a leading end of the bolt are provided with a first pitch;
wherein each of any other adjacent thread portions of the bolt are provided with a second pitch which is different from the first pitch; and
wherein the second pitch is substantially identical with a pitch of each adjacent thread portions of the nut.
In the constructions, the bolt and the nut, beforehand connected to the battery terminal in an integrated manner, will not be disengaged from each other by vibrations, an impact or the like during the transport before this battery terminal is fed to a production line where the nut and the bolt are finally completely fastened together.
Therefore, the battery terminal, incorporated with the bolt and the nut connected thereto in an integrated manner, can be positively stored as one part, and the cost for the parts management can be reduced.